Ice-making and refrigerating system



March 16, 1954 G, MUFFLY ICE-MAKING AND REFRIGERATING SYSTEM s sheets-Sheena; 'y

Filed Aug. 12, 1949 March 16, 1954 G. Mur-'FLY ICE-MAKING AND REFRIGERATING SYSTEM Filed Aug. l2, 1949 3 SheetsfSheet 5 a 5 E ,/a N0 T R.. f1 n@ 2 3 J V 5 Nfr a MMI 5,2% M fw Ww/ y n @,M \\\\\\\\\\m 4 e Z 4.

Patented Mar. 16, 1954 UNITED STATES PATENT OFFICE 11 Claims.

This invention applies to automatic ice making machines of the general type disclosed in my numerous issued patents and patent applications, being an improvement on the apparatus shown in my U. S. patent application Serial No. 50,101, led September 20, 1948, and in my Canadian application S. N. 588,997, led June 13, 1949.

One object of this invention is to provide for inclusion of a water softening device so arranged that recirculating water passes through the water treating material.

Another object is to provide for draining of water from the machine through one outlet.

An additional object is to provide for delivery of ice to a removable ice bunker and to control the machine so that ice production stops in re sponse to the accumulation of ice in the bunker.

A.' further object is to provide a hinged ice chute extension for delivery of ice to a separate bunker with the ice quantity control located on this hinged extension.

An additional object is to arrange the hinged extension so that when lifted from the removable bunker it forms an insulated door closing the outlet of the ice chute portion located within the ice maker cabinet.

Another object is to provide control means associated with the hinged chute-door arranged to stop the ice making machine in response to the lifting of the outside chute to the position in which it serves as a door.

An additional object is to provide an ice quantity control movable between two positions, in one of which it serves to stop the ice maker when a removable ice bunker is full of ice and in the other of which it serves to stop the production of ice upon accumulation of a predetermined Quantity of ice within the ice maker cabinet itself.

An additional object is to so proportion the internal volumes of the ice maker tanks and the overflow tank that their water levels may be allowed to equalize when the machine is idle. thus eliminating the need for a check valve in the water circulating system.

Another object is to provide an ice maker including a storage bin for ice separate from the water circulating system and provided with means for filling separate ice containers from this storage bin by gravity under control of a gate valve. n

An additional object is to provide a screen, grid or other reticulated member of large area through which reirulated water is reuuired to pass on its Way to the water pump, thus preventing accumulations of ice crystals which collect in the cold water from stopping the inlet to the pump.

A further object is to provide for centrifugal separation of minerals from the water by directing the denser portion of the water into a trap, preferably associated withthe pump, so that the impure water may be drained from the machine without draining all of the water therefrom.

A further object is to provide a vertical ice making tank having one horizontal dimension less than twice the thickness of ice which projects into the tank from an ice making surface, thereby reducing the volume of water required to fill the machine and the rate at which water mrst be circulated to make clear ice.

Another object is to arrange ice making survfaces on opposite sides of the flat tank in staggered relation so that full-sized pieces of ice attached to the tank walls may extend beyond the vertical middle plane of the tank and thus cause a greater agitation of water for a given rate of water ilow.

Another object is to provide an ice quantity control operating thermostatically in response to the contact of loose pieces of ice with the flat cover plate of the control, thus eliminating the need for the usual bulb and capillary tube which are subject to damage, particularly when movably located as required for the dual control of ice quantity in a separate bunker and of ice quantity within the machine.

In the accompanying drawings:

Figure 1 is a vertical sectional view of the icemaker with the lower portion which contains the condensing unit and associated parts broken away.

Figure 2 is a diagram of the refrigerating system and controls employed in Figure 1,

Figure 3 is a sectional view showing an alternative design of cabinet to provide more ice storage space within the cabinet itself.

Figure 4 is a partly sectional and partly diagrammatic view showing details of the device for draining water from the system and for centrifugally purifying the water as it recirculates in the system.

Referring now to Figure 1 we see two ilat vertical tanks i9 and I2 which are identical in construction. The identical evaporator coils i4 and iii are wrapped one about each of these tanks. The greater part of each of these coils comprises substantially horizontal legs adjacent the large iiat sides of the tanks. Between these legs of the coils and the outside of the tanks,

there are a large number of thermal contact buttons il, preferably made of copper or other metal having a high thermal conductivity and soldered to both the tank and the coil. When the tank walls are fiat as shown, one side of each button will be flat, but if the ice making areas on the tank walls are formed by embossing outwardly, these contact surfaces of the buttons will be concave to fit the embossed portions of the tank wall. In any event the opposite side of each button is preferably formed to provide an accurate fit and an increased area of contact with the evaporator tube. It is desirable that these buttons iit between the tank wall and the evaporator tube quite accurately so that all three parts may be sweated together with the mini mum thickness of solder for maximum thermal conductivity from the tank wall to the tube.

It is also desirable that the flat tanks Ii! and I2 be formed of relatively thin metal having a relativey low thermal conductivity. A suitable metal is stainless steel and a suitable thickness of the metal is about .020. The thickness of the buttons is preferably such as to hold the tubes 1/8 or more away from the tank wall and it is desirable f that thermal insulation be provided between the tube and the tank wall in the spaces between the buttons.

Figure 1 shows only two of the tanks I0 and I2 and two of the evaporator coi's I4 and If, but it will be understood that any even number of these tanks and their corresponding evaporator coils may be employed. When four or more tanks are employed one half of the evaporator coils will be arranged in parallel to be refrigerated at one time and the other ha`f of the evaporator coils will be arranged in parallel and refrigerated while ice is being melted free from the walls of the tanks served by the first mentioned set of parallel evaporator coils.

It is desirable that the cois I4 and It be identical for economy of manufacture and, as shown in Figure l, this provides for the staggering of the positions of the horizontal legs of the two evaporator coils adjacent to each other, thus pro viding more space for insulation between the adjacent coils. This insulation need not be so thick between adjacent coils which are simultaneously refrigerated, but regardless of the number of 4tanks employed there will be a middle space between an active evaporator and an inactive evaporator where it is desirable to provide a thickness of insulation comparable to that shown between the two coils in Figure l.

In Figure l it is assumed that the right-hand coil Iii is being refrigerated while the left-hand coil I4 is on its defrosting or ice-releasing portion of the cycle. We thus see a number of completed pellets 2G of ice attached to the inner walls of the tank I!) and a few of these pieces of ice floating upwardly to the upper tank 22 to be carried out of this tank through the notch 24 by the flow of water which is produced by the operation of the centrifugal pump 26. Ice is released first from the upper portion of the tank due to the fact that warm high pressure refrigerant liquid is introduced to the upper portion of the coil I4 and flows downwardly therein. This prevents the formation of an ice jam such as might result if the lowermost pellets of ice were released first.

The pump delivers water to the tube 28 which leads to manifolds 30, of which one is attached to the bottom of each of the ice-making tanks. Perforations 32 in the bottoms of the tanks provide for distribution of thiswater flow throughout the length of the tank. Water is delivered to all of the tanks constantly so that agitation is provided during the ice making period and an upward flow of water is provided in the tank or tanks where ice is being released. In a large machine having many tanks it may be desired to provide valve means for stopping the flow of water through the tanks not being refrigerated, as the ice will iioat upwardly when released without the aid of this water flow, but for simplicity such valve means is omitted in Figure 1 which illustrates a small capacity machine having only two ice making tanks.

As the ice floats upwardly into the tank 22 with which all of the ice making tanks are connected, the overflow of water through the narrow outlet gate 24 carries the ice onto the inclined chute 34 which is preferably formed of parallel wires located close enough together to prevent the passage of ice while allowing the overflow water to fal into the top of the water treating cartridge 35. This arrangement of the water treating cartridge is such that all or a substantial part of the circulating water flows through it each time it flows from the tank 22. This method of recirculating water through the cartridge of ion exchange resins, Zeolite or other suitable water softening material solves the problem of preventing the water in the machine from gradually in creasing in mineral content, as it would do if ony the incoming water were passed through the water treating device. This effect of constantly increasing hardness of the unfrozen water results from the fact that the ice contains less mineral than the water from which it is formed wherever only a part of the water is frozen at each cycle. In my design the unfrozen water is recirculated through the water softener to remove those minerals which are rejected by the ice and thus concentrated in the unfrozen water.

During operation the water level in the overflow tank 38 will stand at approximately the level 40 surrounding the cartridge B but will be higher within the cartridge, this difference of level providing the head which causes flow of water through the cartridge. The water level 42 in the upper tank 22 is that prevailing during the operation of the machine, but when the machine including the pump 2S is stopped the water levels 49 and 42 are equalized at a common level indicated by the dotted line 44 due to the fact that water can flow in reverse through the pump while the pump is idle. Upon starting of the pump the water level in the upper tank again assumes the level 42 and the water level in the overflow tank 38 again drops to the operating level Ail.

It will be noted that the manifolds 38, shown as formed of sheet metal welded or soldered to the bottoms of the ice making tanks, are downwardly inclined at their bottoms toward the tube 2S with which they connect. This provides a taper which aids in distribution of water to the several outlet holes 32 and also provides for drainage of water from the ice maker tanks into the tube 28, which in turn drains back to the pump 2S when the plug 4t is removed. In place of this plug there may be a length of tubing provided with a suitabe valve for draining water from the ice maker. Such a tube provides a trap in which a denser fraction of the circulated water is accumulated due to the centrifugal action of the pump. It is, therefore, possible by opening the valve to drain this trap and 4thus remove the denser portion of the water which carries the highest mineral concentration without drainingthe entire system. This is further. explained fin connection-with Figure 4.

The water which is constantly being circulated `over the newly formed ice during operation of the machine will fall to near its freezing point and portions of it may even become subcooled ering the entire bottom ofthe overflow tank 38.

This large area insures against complete stoppage by ice crystals While the holes, or corresponding spaces between wires if 50 is a screen, prevent any accumulationvof ice crystals large enough to interfere with operation o the pump from entering it. y Y

As the ice pellets 20 leave the water and slide downwardly on the inclined chute 34 they drop onto the outside chute 52 and fall therefrom into -a suitable container such as 54, which may be a large insulated box mounted on casters or a smaller container of the totebox variety resting upon a suitable stand or shelf. As the ice falls into this container it naturally builds up in the form of a central heap and slides toward all sides of the container, thus at the center of the box 54 icey may pile up above the side walls, but when leveled off the container will be something lessI 'thanlevel full. As ice builds up to a Vhigh level .near the center of the container some of it will slide back against the plate 56 whichv is attached to the exposed vertical wall of the horizontally hinged outside chute assembly 52. The cover .plate 56 forms the thermally responsive surface of thermostatic switch 60, as will be explained in z connection` with Figure 2. When ice accumulates to a level at which it covers a lower portion of vthe plate 56 the thermostatic switch opens to stop the machine. An attendant noting that the container 54 is full of ice swings the hinged assembly A52 into the position 52 where it serves as an insulated door to close the ice outlet opening of the cabinet. If this is done while the machine is still runing in order tc move a partially filled container 54 ice will accumulate within the space 62 until it contacts what is then the lower portion'A of the plate 52 and this will likewise cause the thermostatic switch Soto open, stopping the machine. While Figure l shows a very small compartment 62 in which ice may accumulate when the door 52,' is closed, it will be understood that a much larger compartment may be provided so .that the machine will operate for many hours with the door 52 in its closed position. Then when an attendant pushes an empty container 54 against the front of the machine and swings the door 52 down to the position 52, a large supply of ice will immediately flow into the container 54. If desired the compartment B2 may be made of suflicient capacity to ll a number of portable containers 54.

Figure 2 shows the refrigerating system of Figure l di'agrammatically, indicating with solid arrows the path of refrigerant flow at the time in the cycle represented by Figure 1, that is with the right-hand evaporator I6 active and the lefthand evaporator i4 being heated for the purpose of releasing ice by means of warm high pressure refrigerant liquid. This liquid leaving the lowermost leg' of coil I4 flows past check valve 64 to the expansion valve 66 from which low pressure liquid refrigerant with less than the usual -percentage of flash gas flows through the check valve 68 into the lowermost coil of evaporator I6. From the uppermost coil of this evaporator vapor flows through the tube T0 and the open solenoid valve 12 to the suction tube 'i4 leading back to the inlet of the motor-compresor unit 16. Compresssed refrigerant vapor ows through the tube lthe liquid line and the suction line as it is desired to retain the specific heat of the liquid for use in thawing off the finished pellets of ice in the left-hand tank l0.

The operation as just described continues until all of the ice pellets in tank. Hl have melted free and iioated out through the chute or are on their way to the chute. The solenoid valve 84 then closes to stop the flow of liquid refrigerant to the idle evaporator i4, but liquid continues to flow through the expansion valve to the active evaporator i6 since the liquid refrigerant in the idle evaporator i4 was under high pressure at the time that the valve 84 closed and this liquid will start evaporating at its pressure drops due to the flow of liquid through the expansion valve. This continues until the upper portion (probably 2/3) of the evaporator [4 is lled with vapor and the lower coils with liquid at a pressure somewhat higher than the normal evaporating pressure. During this period liquid refrigerant collects in the condenser-receiver 88.

Next. the solenoid valve 'i2 closes, the solenoid valve 86 opens and the solenoid valve 88 opens, either simultaneously or in this sequence with a very short time interval between valve actuations. This starts flow of liquid refrigerant through the valve 88 and the tubes 'So and i9 to the uppermost coil of the evaporator i6 which is'thereby filled with high pressure liquid refrigerant, the specific heat of which causes the newly formed ice pellets in the tank I2 to thaw free from'its walls and'float up into the upper tank 22 from which they are delivered to the ice bunker 54. Liquid refrigerant now flows through the check valve 92 to the expansion valve 66 and through it in the same direction as before but thence through the check valve 94 (check valve 68 being now held closed by high pressure liquid in coil i6) to the lowermost coil of the evaporator i4, which now becomes active. Vapor ows from the uppermost coil of evaporator le through the `tubes and 96, the now-open solenoid valve 86 and the tube 'P4 to the suction, port of the sealed motor-compressor unit l. This flow is indicated by broken line arrows in Figure 2.

It will be noted that the arrangement of check valves is such that liquid refrigerant flows through the expansion valve in the same direction when refrigerant flow is reversed through the evaporators. It will also be noted that the heat ernployed in melting the ice pellets free from tank walls is the specific heat of high pressure liquid refrigerant and not the latent heat of Vapor as in the usual hot gas defrost method. This operation continues with reversal of flow after each ice making cycle in one ofthe two tanks lmor I2. Assuming a minute period of ice making and an 18 minute period of feeding hot liquid refrigerant to the idle evaporator for the purpose of releasing ice, we have a two minute period during which liquid refrigerant flow to the idle condenser or receiver and is ready to flow into the evaporator which has just finished its ice making period to start its ice releasing period. There is no thermal loss in uisng the specific heat of liquid to thaw ice off such as there would be if hot refrigerant vapor were used to thaw the ice off. By using the specific heat of the liquid we precool the liquid before it enters the expansionvalve, thus minimizing the amount of flash gas at the inlet to the active evaporator.

It will also be noted that this method of introducing hot liquid refrigerant to the uppermost leg of the evaporator results in releasing ice at the top of the tank before ice is released from the ice-making areas nearer the bottom of the tank. This allows the use of a very narrow tank and makes the system more compact. The narrow tank requires less water flow to produce the desired agitation for making clear ice than would a wider tank. The ice making areas on the tank walls are staggered so that ice pellets forming on one side of the tank do not contact ice pellets forming on the opposite wall of the same tank, even though the ice pellets may grow to a horizontal dimension greater than half the thickness of the tank. This arrangement provides for making a very large number of ice pellets in a compact apparatus. This compactness becomes more evident when the number of ice making tanks is increased, as the same dimensions may be retained for thickness of outer insulated walls and 1 of the overflow tank 38. The machine can be doubled in capacity by adding about V; to the horizontal dimension of Figure 1. In this case two of the evaporator coils will be connected in parallel and the two pairs of parallel coils con- :.56

nected just as the two single coils are in Figure 2. Two of the coils will be active making ice while the other two ar-e heating the ice making areas to release ice or are in the pumping out periodl of the cycle.

The motor 98 seen in Figure 2 is connected in parallel with the motor which operates the compressor and is controlled by a separate thermostatic switch |00, as previously disclosed in my U. S. patent application S. N. 50,101, led September 20, 1948. After start of the system the tube 'i8 warms the bulb |02 to close the switch |00.

Figure 2 shows an enlarged sectional view of the thermostatie control |50 in Figure 1, the position shown being the same as that indicated by solid lines in Figure 1. The bellows or diaphragm |04 is of relatively large diameter and small length so that it covers a considerable area of the metal plate 55, to which it is soldered or brazed. This bellows is not provided with the usual capillary tube and bulb since it operates in response to temperature changes of the cover plate 56. In the position shown in Figure 3, there is a small amount of volatile liquid |06 in the lower portion of the space enclosed by the bellows |04 and plate 56.

Ice accumulating in the bunker 54 and reaching the level of this liquid cools it so that some of the vapor above the liquid condenses, thereby allowing the bellows to contract under the pressure of the spring |08 and causing the contact member I I0 to snap away from the fixed contact member I |2, thus breaking the circuit of the motor which operates the compressor.

In series with the thermostatic switch above described and also seen in Figure 2 is a gravity switch operated by the weight II4. When the switch assembly is turned upside down as occurs when the outer chute 52 of Figure 1 is moved to the position 52' where it acts as a door, this weight causes the contact IIB to leave the contacts I I8 and I I9, opening the circuit of the compressor motor even when the thermostatic switch is closed. y

This gravity operated switch may be omitted, in which case the same thermostatic switch will operate to stop the motor-compressor unit when the outer chute is swung to its upper position to close the ice outlet. With this outlet closed ice will accumulate in the chamber 62 until the uppermost pellets of ice contact the then'lower portion of plate 56 and cool the liquid within the bellows |04, such liquid having moved to what is now the lower side of the bellows. This provides a single thermostatic switch entirely contained within the swinging outer chute and door assembly except for the plate 56 which serves as a flange for its attachment. The connection with the sys-'- tem is entirely by means of a two-wire cable |20 which is amply flexible for allowing the required movement. This may be preferred over the alternative of moving the bulb of a control, which involves bending a capillary tube.

The clock switch |30 seen in Figure 2 may be similar to the one shown diagrammatically in Figure 5 of my copending U. S. patent application S. N. 50,101, filed September 20, 1948, but is equipped with additional contacts for controlling the water pump motor 98 and a drain valve. The clock is preferably of the electric type driven by a motor connected with wires |32 and |33 so that it operates only when switch 60 is closed. One pair of added contacts connects wire I 32 with wire |34 to control the pump motor 38 and the other pair connects wire |32 with wire |35 to actuate the drain valve described later herein. The pump motor may be controlled by a Yclockoperated switch in combination with or in place of the thermostatic switch |00. Where it is desired to circulate the water continuously during the freezing operation for the purpose of making clear ice it is not necessary to connect the motor 88 with the clock switch, but in some cases it may not be considered important to make clear ice, in which event it is only necessary to operate the motor 9B during relatively short periods to float the ice from tank 22.

The wire |32, connected with one side of the line, also connects with switches controlling .the various solenoids of valves |2, 84, 86 and 88. The other contact of each switch is connected with one of the solenoids, wire |38 being connected with the solenoid of valve 84, wire |39 with the solenoid of valve 88, wire |40 with the solenoid of Valve BS and wire IGI with the solenoid of valve l2. The connections |42 of the solenoids all lead back to the opposite side of the line. As shown in Figure 2 the thermostatic switch |00 will close soon after the system starts and thereafter the operation of pump motor '98 9 will be under control of the clock-operated switch.

The condenser-receiver Si) is shown as a plain cylinder cooled by a water coil wrapped around it instead of by the usual internal water coil employed in water cooled condensers. This modified form of water cooled condenser is designed to overcome objections which have been raised by health authorities in ycertain cities Where -it is felt kthat there should `be two thicknesses of metal between the cooling water and the refrigerant to minimize the rather remote hazard of a leak which allows refrigerant to enter the water system.

Figure -3 shows a modification of Figure 1 in' 'which the compartment 62 is greatly enlarged and identified by the numeral 62. The hing-ed outside chute 52 is omitted and in place of the thermostat 65| a conventional thermostat is employed having a brflb ist retained by the spring clip ist in position to be affected by accumulation of ice in the compartment '62 up to this level. A door id@ covers the compartment 62' and closes the cabi-net. This modication provides for storing a large quantity of ice within the cabinet itself and this ice is delivered by gravity thru the opening |50 as required.

A special forlr'. of gate is provided for the opening Iil to overcome the diiculty experienced with sliding, swinging or rotating gate members, the operation of which may be blocked by pieces of ice caught inthe opening as the gate closed. lThe hollow annular member 152, formed oi rubber or other flexible material, is expanded inwardly by the `liquid to close the opening. When it is desired to let ice flow into a portable -container such as till the handie liii is pulled outwardly, moving pli-ragni |5S against action of `the spring 1| sii,

causing the liquid e to flow from the annular gate member thru the tube 52. This causes the -annular :member |52 to collapse, leaving an opening thru which the ice pellets now into the tote box or .other container 15. When `the handle li is released the spring it@ actuates diaphragm i543 to force `the liquid baci; into' the member .i552 and recloses the opening |59. in thev event that a piece of ice is .caught between opposed sides oi themember .|52 as the opening is closed the spring .|50 will maintain pressure on the liquid `so that the opening is coinpletely closed when this piece of ice melts away. Since the closure member L52 is ilexible no ,harm is done by any ,ice caught by it .as it closes.

The contact surfaces of the member'V |52 need not be such as to form a water-tight closure. In fact these surfaces may be intentionally corrugated so that water will thru .the opening |50 when the iiexible gate is closed. ,A drip pan |64, which may be Vmovable for emptyn ing or connected with the drain, serves to catch such wat-er drips thru the opening when there is no `rice container 54| in place. To provide for support of the container 354' and to minimize slopping of water if the pan |621 -i-s movable, 1 have shown a grid member 166, v'similar to the solid grids Vformerly `used in ice trays. 'This grid is dush with or extends slightly higher than the walls .of the pan |64., thus providing a suitable support for the tote box 54', it will be evident that the cabinet-design may be varied at the designers option to provide for filling `very large containers 54 mounted upon wheels or .to provide for filling smaller containers,1 leven dawn l0 to individual drinking glasses, without departing from the spirit of this invention.

Figure 3 also shows in elevation a portion of the insulated cover |63 of which a portion is seen in section in Figure 1. Extending downwardly from this cover isa drain tube |73 which takes the place of the plug |55 vseen in Figure i. The valve |12 connecting with this drain tube may be manually operated or arranged for automatic operation as described in connection with Figure 4.

In Figure 4 we see an enlarged ksection of the lower portion of the pump 25, the drain tube Il@ and the drain valve |12 with electrical connections for operating the valve. The valve member |74 is lifted by the armature |76 of the solenoid |18 lto allow water to drain from the tube |70 to a suitable receptacle or drain con nection. The solenoid is actuated by manual closing of the switch lil or by closing of the clock-actuated switch yi'-Z which is contained within the assembly |36. Normally7 the manual switch its is employed when it is desired to drain the apparatus completely, and the clock actuated L switch |82 is employed during operation to dispose of that portion of the wtaer contained within the tube |10. When desired to wash the system out and drain it more rapidly the cap' |83 which Jforms the seat for valve |74 maybe removed, taking with it .the valve and solenoid armature V16.

The impurities of water which interfere with making clear ice are mainly minerals which are more .dense than the water and therefore in- 1 crease lthe density of water in which they are dissolved. The pump 26, being .of the centrifugal type will tend to throw the harder frac tion of the 4water against the periphery of the chamber, causing such water to flow downwardly thru the tube 184. Gravity then aids in conoentrating the mineral impurities in .the lower portion `of the tube ill! and within the .space immediately above the valve |14. A small hole |86 is provided to allow limited Acirculation of water downwardly thru the tube |84 and upwardly thru the tube Lilo to the pump. The hole |86 and the hole 1:88 may be toppositely inclined as shown to aid in the promotion .of ksuch .circulation, which should be slow enough to allow ,av

heavier fraction of the water to collect in the bottom 'of the tube 1| ld; as above explained.

During regular .operation of the system, once during each .ice making cycle `or less ire quently if the water supply is not too hard, the

solenoid |18 is energized for ya very short .periodI to allow approximately the volume of water .contained within the tube il@ and the valve lchamber below .it to escape.. This removes `.the lportion of the water containing the highest mineral concen-l tration, thus .olsetting the .concentration of mineral within the nnirozen water which .progresses with each ice vmaking cycle.. iushing methed ,may be employed in Acombination with the demineralizer 35 or either one may be vused alone, depending upon the hardness of the water supply, :the desire for economy, and the importance placed ,upon the making of. clear ice.

Water is admitted from the lcity water system to make up for the flushing to purify the water and for the ice removed from `the circulating Water; ,This under control :of the valve |99 operated by the iloat |52 seen in Figure l., las .explained in my S. application S. 1N. 550,1.0l,l tiled September 20., 31948, wherein a similar iloat valve is disclosed. The float and valve are arranged to acvaoiv 11 maintain approximately the level 40 within the overflow tank 48 during operation of the system. Naturally, the float valve cannot open while the water level is equalized at 44.

The method of introducing warm liquid refrigerant into an evaporator suddenly at the start of the defrosting period when there is very little cold liquid refrigerant in it aids in bringing warm liquid refrigerant into heat exchange with all icemaking areas sooner than would be the case if the Warm liquid were introduced gradually or the evaporator were nearly full of cold liquid refrigerant when the defrosting period is started.

The buttons I8 are, as explained, preferably of round section and might be machined by cutting from a round bar and milling out the recess to t the tube with a milling cutter the diameter of the tube, but they are preferably made of copper, which is expensive and hard to machine, so I propose to make them by an upsetting operation. This could be called forging particularly if made from flat stock, or "die casting if molten or semi-fluid copper is used. In any event the proposal is to form these buttons with a mold, die or upsetting tool rather than by machining, thus saving both labor and material.

While the drawings herewith show ice floated upwardly from the ice-making areas, it Will be seen from my U. S. Patent No. 2,359,780, issued October l0, 1944, that I also have in mind dropping ice from the surfaces on which it is frozen. This requires very little change from the drawings of the present application. The tanks I and I2 would in that case have no bottoms and become vertical flues through which water trickles downwardly from the jets 32, which would then be located at the top. The chute 34 for separating ice from the water would be located below the vertical tanks or ilues I0 and I2 and the tank 38 would be below the chute. This design would add something to the overall height of the ice-maker unless the condensing unit were then located at one side of instead of below the icemaking apparatus.

I claim:

1. In an ice-making apparatus, a centrifugal pump comprising a housing and an impeller, means forming an upwardly directed discharge passage for said pump, means forming a downwardly directed inlet passage to said pump, and drain means associated with said pump, the last said means and said passages being so constructed and arranged as to provide for simultaneously drainingall liquid from said housing and from both of said passages.

2. In a Water circulating and purifying apparatus, a centrifugal pump, a housing forming a part of said pump, a chamber associated with said housing for collection of a denser portion of the Water circulated by said pump, and means for draining water from said chamber.

3. In a water circulating and purifying apparatus, a centrifugal pump, a housing forming a part of said pump, a chamber associated with said housing for collection of a denser portion of the water circulated by said pump, means for draining water from said chamber, and periodically actuated means for opening and closing said draining means.

4. In an automatic ice maker of the flotation type, a nat tank in which a plurality of relatively small pieces of ice are formed on one side of a thin ilat metal wall, a refrigerating system including an evaporator, and a plurality of contact buttons shaped to t said evaporator and the dry side of said Wall opposite the areas 'on which said pieces of ice are formed, said buttons being formed by flow of the metal from which they are made.

5. In an ice-making apparatus. means for freezing a relatively large number of relatively small pieces of ice, control means regulating the releasing of said pieces of ice from the surfaces on which they are frozen, an energy source for actuating said control means, a centrifugal pump for circulating Water over said pieces of ice while they are in process of freezing, and screen means of relatively large area fixed in the path through which said Water is required to ow on its way to said pump, said screen means being adapted to prevent floating particles of ice from clogging the inlet to said pump.

6. In an ice-making system, a flat vertical tank having a plurality of ice-making surfaces arranged at various levels on one of its larger vertical sides, means for circulating water so that it flows over said surfaces, means for refrigerating said surfaces to cause a portion of said Water to be frozen thereon, means for stopping said refrigeration and introducing Warm refrigerant to said refrigerating means to thaw ice free from said surfaces, and means for separating said freed ice from the circulating water.

7. In an ice-making apparatus, a compartment in which separate pieces of ice are frozen, a centrifugal pump located at a lower level than said compartment and having a discharge passageway upwardly directed toward and opening into the bottom portion of said compartment, a tank positioned at a higher level than said pump and arranged to receive water passing through said compartment from said pump, said pump having an inlet passageway upwardly directed toward and opening into the bottom portion of said tank whereby water may pass from said tank to said pump, drain means for said pump, said drain means being in fluid flow communication with both said inlet and said discharge passageways whereby said drain means Will simultaneously and completely drain water from said compartment and said pump and said tank.

8.-In an ice maker of the flotation type, a ilatsided vertical tank having a pair of spaced vertical walls, an evaporator for refrigerant exteriorly of said tank and spaced outwardly of said Walls, spaced metallic means thermally connecting said evaporator to said walls solely at spaced locations to provide a plurality of separate spots cooled by said evaporator to form a plurality of spaced ice pieces, said spots on one of said walls being in staggered relationship to said spots on the other of said walls, said Walls being spaced apart a distance not greater than two times the maximum expected thickness of said ice pieces, means for circulating Water upwardly through said tank and over said walls whereby portions of said circulated Water will be frozen upon said spots and other portions of said circulated water will wash away air and other impurities from said frozen water pieces, said formed ice portions acting to increase the resistance to low of said other Water portions whereby to promote the removal of said air and other impurities, and means for supplying warm refrigerant to said evaporator at the uppermost of said spots and then to lower ones of said spots to provide for freeing said ice pieces progressively from said Walls downwardly from the top of said tank whereby water circulating upwardly through said outlet and said container inlet for pumping water from said tank into said container, a storage chamber for the small ice pieces located on the opposite side of said tank from said container and having an inlet opening for ice adjacent its upper portion, an inclined grille extending downwardly from said container outlet over said tank inlet and to said chamber inlet whereby ice pieces discharging from said container will move into said chamber and water discharging from said containerfwill flow into said tank, a gate controlling the passage of ice pieces over said grille and movable from a position to block the passage of such pieces into said chamber and into a position within said chamber, and temperature responsive means carried on one surface of said gate and responsive to the presence of ice pieces in heat exchange relation therewith for stopping the production of ice.

10. In an ice-making apparatus, a tank for the storage of water to be frozen, means outside of said tank for freezing a portion of said water, a demineralizer located in said tank and extending above the water level thereof for removing minerals from water, and means for recirculating said water from said tank through said freezing means to overflow therefrom into said demineralizer and flow therethrough to complete its circuit.

11. In an ice-making apparatus, a centrifugal pump to circulate water, a trap directly connected Ywith the interior of said pump to isolate a denser portion of the water, a valve for draining said denser water from the system for the purpose of removing impurities from the water to be frozen in making ice, and a periodically energized power element for actuating said valve.

- GLENN MUFFLY.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 703,315 Smith June 24, 1902 703,353 Smith June 24, 1902 1,437,518 Hemphill Dec. 5, 1922 1,811,651 Schlachter June 23, 1931 1,861,839 Burks June 7, 1932 1,931,347 Gay Oct. 17, 1933 1,963,842 Gay June 19, 1934 1,994,183 Warner Mar. 12, 1935 2,063,771 Taylor Dec. 8, 1936 2,133,521 Wussow Oct. 13, 1938 2,145,774 Mufy Jan. 31, 1939 2,145,777 Muilly Jan. 31, 1939 2,149,000 Udell Feb. 28, 1939 2,221,212 Wussow Nov. 12, 1940 2,299,414 Spiegl Oct. 20, 1942 2,310,468 Short Feb. 9, 1943 2,340,721 Whitney Feb. 1, 1944 2,349,451 Motz May 23, 1944 2,364,016 Wussow Nov. 28, 1944 2,418,572 Brennan Apr. 8, 1947 2,443,203 Smith June 15, 1948 2,466,831 Vanvleck Apr. 12, 1949 

